Towed rotary hay rakes for raking and stacking forage with both mechanical and hydraulic hoisting, or positioning, apparatuses currently exist. Such rakes typically consist of a rotary gearbox which rotates a set of rake arms positioned like spokes of a wheel about a common axis, a towbar to affix the rake to a tractor, and a wheeled support structure below the gearbox to support the gearbox and facilitate movement of the rake. During operation, the rake arms typically sweep completely around the wheel base of the support structure.
As is well-known, a feature that these rotary hay rakes have in common is the ability to assume different positions. In particular, the rake arms, which have the function of raking the forage, can be lowered to a working position so that the tips of the rake arms contact the crop for the raking operation and can be raised to an upper position for maneuvering and transport on the roadway.
The currently known positioning systems, whether mechanical or hydraulic, have drawbacks, however. Specifically, those rotary hay rakes with mechanical hoisting apparatuses generally possess only a limited range of movement and are difficult to maneuver. Furthermore, the operator may be required to get off of the tractor which tows the hay rake in order to operate the hoisting apparatus. Other currently known rotary hay rakes have hydraulic hoisting apparatuses, but these apparatuses are not optimally mounted on the hay rake. Because of difficulties in transferring power from above the gearbox of the rotary hay rake to a mechanism located on the support frame below the gearbox, a known hydraulic lifting mechanism for raising and lowering the hay rake includes a hydraulic cylinder that is mounted underneath the gearbox. Such positioning, however, is inconvenient and undesirable because the underside of the gearbox is not easily accessible.
Another problem with currently known positioning devices, whether mechanically or hydraulically operated, is that they do not always position the hay rake, in particular the rake arms, in an orientation which is parallel to the ground, as is desirable for optimal functioning. Because the hay rake is attached to the towing tractor by means of a tow bar, the orientation of the tow bar with respect to the tractor and the hay rake can deleteriously affect the positioning of the hay rake. For example, the tow bar tends to vary the hay rake's longitudinal inclination according to the greater or lesser height at which the tow bar has been attached to the tractor and according to the greater or lesser length of the tow bar. Therefore, it may not be possible to position the hay rake, in particular the rake arms, in a parallel orientation to the ground.
Whereas fine adjustment apparatuses may be available for adjusting the longitudinal inclination of the hay rake to overcome the tow bar effects addressed above, these types of adjustment apparatuses have drawbacks as well. Although the apparatuses may be effective at leveling the hay rake's trim when the hay rake is in the lower work position, they are not able to adjust for variations in the hay rake's inclination, which cause it not to be positioned parallel to the ground, after the hay rake has been moved to the upper maneuvering and transport position.
The problems described above are solved by the rake positioning apparatus of the present invention, which provides for an improved mounting location for an actuator included in the positioning apparatus, e.g., an easily accessible hydraulic cylinder which is mounted above the gearbox of the hay rake, a means for maintaining the hay rake in a parallel orientation to the ground when it is in both the lower working position and the upper maneuvering and transport position, and the convenience and practicality of remote control which is typical of hydraulic controls, thus eliminating any need for the operator to get down from the tractor and approach the hay rake to operate it or adjust it.